On the verse "Your
two breasts are like two fawns, twins of the gazelle" (Songs 4:5),
Rashi comments that the expression shnei shadecha refers to the two
stone tablets. They are described as "twins" because they
were both of identical dimensions and contained five commandments each.
The commandments parallel each other.

The injunction not to murder corresponds to the commandment
that "I am the Lord Your G-d," for the murderer diminishes
the stature of G-d by destroying His handiwork.

The commandment not to have other gods corresponds to
the prohibition of adultery, because the adulteress practices deceit
of her husband, whereas the idol-worshipper practices infidelity against
his Maker.

The commandment not to use the name of G-d in vain corresponds
to the prohibition of stealing; in the end every thief will resort to
a false oath to deny his deed.

The commandment to observe Shabbat and keep it holy corresponds
to the prohibition of being a false witness; anyone who does not observe
Shabbat testifies that G-d did not create the universe and rest on the
seventh day.

The commandment to honor one's father and mother corresponds
to the commandment not to covet; he who covets someone else's wife will
ultimately sire children who will repudiate and curse him instead of
honor him.

[Selected with permission and adapted
from the three-volume English edition of Shney Luchot HaBrit -- the
Sh'lah, as translated, condensed, and annotated by Eliyahu Munk.]

(Chassidic Masters)

The
Midrash says that the Torah was given to us in three stages: through fire, through
water and in the dessert. These three stages are symbolic and they teach us how
one merits the Torah. Fire: the fiery arousal of longing for their Father in Heaven
that burns in the heart of the Jew; water: moderation, contemplation and clarity
of thought, to think in the ways of Torah, in the right spirit and mind; desert:
doing without all the pleasures and desires of this world that hinder the person
in reaching perfection. (Shem MiShmuel)

Why
is Shavuot called "The Time of the Giving of the Torah" as opposed to
"Receiving the Torah"? It is because on the sixth of Sivan was the time
of the giving of the Torah, more than three thousand years ago, but the time of
the receiving of the Torah never ceases; every day a Jew has to receive the Torah
anew. (Chidushei HaRim)

Every festival the Torah informs
us that one has to sacrifice a sin offer. Only on the festival of Shavuot is the
word 'sin' not mentioned. For on the festival of Shavuot, the day of the receiving
of the Torah, all Jews are like the convert "newborn", and so free of
all sin. (R Levi Yitzchak of Berditchev)

(Chabad Rebbes)

A great emphasis is placed (see Ex.
19:18) on the fire that accompanied the Giving of the Torah. This teaches us that
all matters concerning Torah-study, mitzvah-observance, prayer, and every manner
of serving and acknowledging G-d, must be carried out in "fire": with
vital warmth, and with flaming desire to fulfill G-d's will. Our power to do so
is derived from the fire on the mountain that burned during the Giving of the
torah. (Sefer HaMaimorim 5701)

The Torah was given
on a mountain, to teach that the learning of Torah and going in G-d's ways should
give us a certain emotional elevation. At the same time one has to be careful
not to fall prey to arrogance. That is the meaning of 'opposite the mountain':
to be exceedingly careful to oppose the aggrandizement that can come from Torah
learning and knowledge. (Maimarim Taf Shin Gimmel)

Some Laws and Customs (from Ascent Quarterly)

SUGGESTED
ACTIVITIES for SHAVUOT

1) Switch into high gear!
2) Stay up all night studying Torah to rectify our mistake. 3)
Towards dawn, immerse in a mikvah (or ocean or pool), but don't drive there–it's
Yom Tov! 4) Go to a shul and hear the Ten Declarations. Try to
bring others too–especially Jewish children, for they were our guarentors at the
first Giving of the Torah and they too will benefit by experiencing it now.
Accept the Torah unconditionally with joy and sincerity. 5) Eat some
dairy foods. When we were given the Torah (including the laws of kashrut),
we realized that our cooking vessels were not kosher, so until we kashered
them we ate only dairy products. 6) Read the Book of Ruth: a) King
David, her descendant, died on Shavuot; b) Ruth was a convert and at Sinai we
were like converts –G-d transformed us from ordinary people to a special nation.